Abstract:

Disclosed is a method and device to increase the cooling load that can be
provided by a refrigerant-based thermal energy storage and cooling system
with an improved arrangement of heat exchangers. This load increase is
accomplished by circulating cold water surrounding a block of ice, used
as the thermal energy storage medium, through a secondary heat exchanger
where it condenses refrigerant vapor returning from a load. The
refrigerant is then circulated through a primary heat exchanger within
the block of ice where it is further cooled and condensed. This system is
known as an internal/external melt system because the thermal energy,
stored in the form of ice, is melted internally by a primary heat
exchanger and externally by circulating cold water from the periphery of
the block through a secondary heat exchanger.

Claims:

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15. (canceled)

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17. (canceled)

18. A method of providing load cooling with a refrigerant-based thermal
energy storage and cooling system comprising the steps of:circulating a
refrigerant between a condensing unit and a primary heat exchanger in a
primary cooling loop during a first time period;condensing said
refrigerant with said condensing unit; and,expanding said refrigerant in
said primary heat exchanger that is constrained within a tank filled with
a fluid capable of a phase change between liquid and solid during said
first time period to freeze a portion of said fluid within said tank and
create a cooled fluid and a frozen fluid;circulating said refrigerant
between said primary heat exchanger and a load heat exchanger in a
secondary cooling loop during a second time period;condensing said
refrigerant in said primary heat exchanger utilizing cooling from said
frozen fluid;expanding said refrigerant in a load heat exchanger to
provide said load cooling; and,circulating said cooled fluid to a
secondary heat exchanger in thermal communication with said secondary
cooling loop in said second time period to reduce the enthalpy of said
refrigerant in said secondary cooling loop.

19. The method of claim 18 further comprising the steps of:reducing the
pressure of said refrigerant with a refrigerant management unit placed in
said primary cooling loop between said condensing unit and said primary
heat exchanger;accumulating said refrigerant in a universal refrigerant
management vessel placed in said primary cooling loop.

20. The method of claim 19 further comprising the step of:reducing the
pressure of said refrigerant with a mixed-phase regulator within said
refrigerant management unit.

21. The method of claim 19 further comprising the steps of:circulating
said refrigerant from said refrigerant management unit to said secondary
heat exchanger;lowering the enthalpy of said refrigerant with said cooled
fluid with said secondary heat exchanger; and,transferring lower enthalpy
refrigerant to said load heat exchanger.

22. The method of claim 19 further comprising the steps of:receiving high
enthalpy refrigerant from said load heat exchanger with said primary heat
exchanger and said secondary heat exchangertransferring lower refrigerant
to said refrigerant management unit.

23. The method of claim 18 further comprising the step of:pumping said
refrigerant with a liquid refrigerant pump to provide said circulation in
said primary refrigerant loop.

24. The method of claim 18 further comprising the step of:circulating said
cooled fluid to said secondary heat exchanger in thermal communication
with said primary cooling loop in said first time period to reduce the
enthalpy of said refrigerant in said primary cooling loop.

25. The method of claim 18 further comprising the step of:utilizing said
thermal energy storage and cooling system to boost said load cooling of
an air conditioning system.

26. The method of claim 18 further comprising the step of:utilizing said
thermal energy storage and cooling system to shift at least a portion of
the power consumption time period of an air conditioning system.

27. The method of claim 18 further comprising the step of:excluding said
secondary heat exchanger from said secondary cooling loop with at least
one valve.

28. The method of claim 18 further comprising the step of:utilizing a
secondary cooling source in thermal communication with said secondary
heat exchanger that is placed in thermal contact with said refrigerant to
reduce the enthalpy said refrigerant.

29. The method of claim 18 further comprising the step of:locating said
secondary heat exchanger within said tank and in thermal communication
with said fluid.

30. The method of claim 18 further comprising the steps of:receiving said
fluid from said secondary heat exchanger with a tertiary heat exchanger
that facilitates additional thermal contact between cooled said fluid and
said refrigerant to further reduce the enthalpy of a portion of said
refrigerant; and,returning warmed said fluid to said tank.

31. The method of claim 18 further comprising the steps of:reducing the
enthalpy of said refrigerant with a tertiary heat exchanger connected in
parallel with said secondary heat exchanger that additionally facilitates
thermal contact between cooled said fluid and said refrigerant;
andreturning warmed said fluid to said tank.

32. The method of claim 18 further comprising the steps of:receiving said
fluid from said secondary heat exchanger with a plurality of heat
exchangers that facilitate additional thermal contact between cooled said
fluid and said refrigerant to further reduce the enthalpy of a portion of
said refrigerant; and,returning warmed said fluid to said tank.

33. The method of claim 18 further comprising the steps of:reducing the
enthalpy of said refrigerant with a plurality of heat exchangers
connected in parallel with said secondary heat exchanger that
additionally facilitates thermal contact between cooled said fluid and
said refrigerant; andreturning warmed said fluid to said tank.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001]This application is a divisional of U.S. patent application Ser. No.
11/138,762, filed on May 25, 2005. This application is based upon and
claims the benefit of U.S. provisional application No. 60/574,449,
entitled "Refrigerant-Based Energy Storage and Cooling System with
Enhanced Heat Exchange Capability", filed May 25, 2004, the entire
disclosure of which is hereby specifically incorporated by reference for
all that it discloses and teaches.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]The present invention relates generally to systems providing stored
thermal energy in the form of ice, and more specifically to ice storage
cooling and refrigeration systems.

[0004]2. Description of the Background

[0005]With the increasing demands on peak demand power consumption, ice
storage has been utilized to shift air conditioning power loads to
off-peak times and rates. A need exists not only for load shifting from
peak to off-peak periods, but also for increases in air conditioning unit
capacity and efficiency. Current air conditioning units having energy
storage systems have had limited success due to several deficiencies
including reliance on water chillers that are practical only in large
commercial buildings and have difficulty achieving high-efficiency. In
order to commercialize advantages of thermal energy storage in large and
small commercial buildings, thermal energy storage systems must have
minimal manufacturing costs, maintain maximum efficiency under varying
operating conditions, emanate simplicity in the refrigerant management
design, and maintain flexibility in multiple refrigeration or air
conditioning applications.

[0006]Systems for providing thermal stored energy have been previously
contemplated in U.S. Pat. No. 4,735,064, U.S. Pat. No. 4,916,916, both
issued to Harry Fischer, U.S. Pat. No. 5,647,225 issued to Fischer et al,
and U.S. patent application Ser. No. 10/967,114 filled Oct. 15, 2004 by
Narayanamurthy et al. All of these patents utilize ice storage to shift
air conditioning loads from peak to off-peak electric rates to provide
economic justification and are hereby incorporated by reference herein
for all they teach and disclose.

SUMMARY OF THE INVENTION

[0007]An embodiment of the present invention may comprise a
refrigerant-based thermal energy storage and cooling system comprising: a
condensing unit, the condensing unit comprising a compressor and a
condenser; a refrigerant management unit connected to the condensing
unit, the refrigerant management unit that regulates, accumulates and
pumps refrigerant; a load heat exchanger connected to the refrigerant
management unit that provides cooling to a cooling load by increasing the
enthalpy of the refrigerant; a tank filled with a fluid capable of a
phase change between liquid and solid and containing a primary heat
exchanger therein, the primary heat exchanger being connected to the
refrigerant management unit that uses the refrigerant from the
refrigerant management unit to cool the fluid and to freeze at least a
portion of the fluid within the tank; and, a secondary heat exchanger
connected to the load heat exchanger that facilitates thermal contact
between the cooled fluid and the refrigerant thereby reducing the
enthalpy of the refrigerant, and returns the warmed fluid to the tank.

[0008]An embodiment of the present invention may also comprise a method of
providing load cooling with a refrigerant-based thermal energy storage
and cooling system comprising the steps of: condensing a first expanded
refrigerant with a condensing unit to create a first condensed
refrigerant; supplying the first condensed refrigerant to an evaporating
unit constrained within a tank filled with a fluid capable of a phase
change between liquid and solid; expanding the first condensed
refrigerant during a first time period within the evaporating unit to
freeze a portion of the fluid within the tank and create a cooled fluid,
a frozen fluid and a second expanded refrigerant; circulating at least a
portion of the cooled fluid through a secondary heat exchanger in a
second time period to reduce the enthalpy of the second expanded
refrigerant and create a lower enthalpy refrigerant; circulating the
lower enthalpy refrigerant through the evaporating unit within the frozen
fluid to condense the lower enthalpy refrigerant and create a second
condensed refrigerant; and, expanding the second condensed refrigerant to
provide the load cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]In the drawings,

[0010]FIG. 1 illustrates an embodiment of a refrigerant-based thermal
energy storage and cooling system with enhanced heat exchange capability.

[0011]FIG. 2 illustrates an embodiment of a refrigerant-based thermal
energy storage and cooling system with enhanced heat exchange capability.

[0012]FIG. 3 illustrates an embodiment of a refrigerant-based thermal
energy storage and cooling system with multiple enhanced heat exchangers.

[0015]While this invention is susceptible to embodiment in many different
forms, there is shown in the drawings and will be described herein in
detail specific embodiments thereof with the understanding that the
present disclosure is to be considered as an exemplification of the
principles of the invention and is not to be limited to the specific
embodiments described.

[0016]As shown in FIG. 1, an embodiment of a refrigerant-based thermal
energy storage and cooling system is depicted comprising the five major
components that define the system. The air conditioner unit 102 utilizes
a compressor 110 and a condenser 111 to produce high-pressure liquid
refrigerant delivered through a high-pressure liquid supply line 112 to
the refrigeration management unit 104. The refrigeration management unit
104 is connected to a thermal energy storage unit 106 comprising an
insulated tank 140 filled with fluid (e.g. water) and ice-making coils
142. The air conditioner unit 102, the refrigeration management unit 104
and the thermal energy storage unit 106 act in concert to provide
efficient multi-mode cooling to the load unit 108 comprising a load heat
exchanger 108 (indoor cooling coil assembly) and thereby perform the
functions of the principal modes of operation of the system. A
circulation loop to a secondary heat exchanger 162 acts to circulate and
destratify fluid 152 within the insulated tank 140 and draw heat from
refrigerant leaving the load heat exchanger 123.

[0017]As further illustrated in FIG. 1, during one time period (ice
building) the air conditioner unit 102 produces high-pressure liquid
refrigerant delivered through a high-pressure liquid supply line 112 to
the refrigeration management unit 104. The high-pressure liquid supply
line 112 passes through an oil still/surge vessel 116 forming a heat
exchanger therein. The oil still/surge vessel 116 serves a trilogy of
purposes: it is used to concentrate the oil in the low-pressure
refrigerant to be returned to the compressor 110 through the oil return
capillary 148 and dry suction return 114; it is used to store liquid
refrigerant during the second time period (cooling mode); and, it is used
to prevent a liquid floodback to compressor 110 immediately following
compressor 110 startup due to a rapid swelling of refrigerant within the
ice freezing/discharge coils 142 and the universal refrigerant management
vessel 146. Without the oil still/surge vessel 116, oil would remain in
the system and not return to the compressor 110, ultimately causing the
compressor 110 to seize due to lack of oil, and the heat exchangers also
become less effective due to fouling. Without the oil still/surge vessel
116, it may not be possible to adequately drain liquid refrigerant from
the ice freezing/discharge coils during the second time period (cooling
mode) in order to utilize nearly the entire heat transfer surface inside
the ice freezing/discharge coils 142 for condensing the refrigerant vapor
returning from the load heat exchanger 123.

[0018]Cold liquid refrigerant comes into contact with an internal heat
exchanger that is inside of oil still/surge vessel 116, a high-pressure
(warm) liquid resides inside of the internal heat exchanger. A vapor
forms which rises to the top of the still/surge vessel 116 and passes out
vent capillary 128 (or an orifice), to be re-introduced into the wet
suction return 124. The length and internal diameter of the vent
capillary 128 limits the pressure in the oil still/surge vessel 116 and
the mass quantity of refrigerant inside the oil still/surge vessel 116
during an ice building time period.

[0019]When activated during a second time period, a liquid refrigerant
pump 120 supplies the pumped liquid supply line 122 with refrigerant
liquid which then travels to the evaporator coils of the load heat
exchanger 123 within the load unit 108 of the thermal energy storage and
cooling system. Low-pressure refrigerant returns from the evaporator
coils of the load heat exchanger 123 via wet suction return 124 to an
accumulator or universal refrigerant management vessel (URMV) 146.
Simultaneously, the partially distilled oil enriched refrigerant flows
out the bottom of the oil still/surge vessel 116 through an oil return
capillary 148 and is re-introduced into the dry suction return 114 with
the low-pressure vapor exiting the universal refrigerant management
vessel 146 and returns to the air conditioner unit 102. The oil return
capillary 148 controls the rate at which oil-rich refrigerant exits the
oil still/surge vessel 116. The oil return capillary, which is also
heated by the warm high-pressure liquid refrigerant inside the
high-pressure liquid supply line 112, permits the return of oil to the
oil sump inside compressor 110.

[0020]Additionally, the wet suction return 124 connects with the upper
header assembly 154 that connects with bifurcator 130 to supply
low-pressure refrigerant to the system from the mixed-phase regulator
132. The mixed-phase regulator 132 meters the flow of refrigerant within
the system by incorporating a valve (orifice) that pulses open to release
liquid-phase refrigerant, only when there is sufficient quantity of
liquid within the condenser 111. This mixed-phase regulator 132 reduces
superfluous vapor feed (other than flash gas which forms when the
pressure of saturated high-pressure liquid decreases) to the universal
refrigerant management vessel 146 from the compressor 110, while also
dropping the required pressure from the condenser pressure to the
evaporator saturation pressure. This results in greater overall
efficiency of the system while simplifying the refrigerant management
portion 104 of the gravity recirculated or liquid overfeed system. It is
therefore beneficial to have a regulated flow controller that can
regulate the pressure output, or meter the flow of the refrigerant, by
controlling the flow independently of temperature and vapor content of
the refrigerant. This pressure, or flow control, is performed without
separate feedback from other parts of the system, such as is performed
with conventional thermal expansion valves.

[0021]The insulated tank 140 contains dual-purpose ice freezing/discharge
coils 142 arranged for gravity recirculation and drainage of liquid
refrigerant and are connected to an upper header assembly 154 at the top,
and to a lower header assembly 156 at the bottom. The upper header
assembly 154 and the lower header assembly 156 extend outward through the
insulated tank 140 to the refrigeration management unit 104. When
refrigerant flows through the ice freezing/discharging coils 142 and
header assemblies 154 and 156, the coils act as an evaporator while the
fluid/ice 152 (phase change material) solidifies in the insulated tank
140 during one time period. The ice freezing/discharging coils 142 and
header assemblies 154 and 156 are connected to the low-pressure side of
the refrigerant circuitry and are arranged for gravity or pumped
recirculation and drainage of liquid refrigerant. During a second time
period, warm vapor-phase refrigerant circulates through the ice
freezing/discharging coils 142 and header assemblies 154 and 156 and
condenses the refrigerant, while melting the ice.

[0022]As heat is transferred from the ice freezing/discharging coils 142
to the surrounding ice, a layer of water forms around the annulus of the
individual coils 142. Once this layer of water forms a sufficient
envelope around a coil, it begins to act as an insulator between the ice
freezing/discharging coils 142 and the ice block. This condition will
persist until such a time when the water annulus becomes large enough for
considerable water circulation to overcome this localized thermal
stratification. In order to compensate for the inability of the system to
produce high levels of instantaneous cooling load, the outer surface of
the ice block is additionally utilized.

[0023]Within the insulated tank 140, the entirety of the water is not
frozen during the ice build cycle, and therefore, an amount of water
continuously surrounds the block of ice. At the bottom of the tank, this
water is very near the freezing point (approximately 33-34° F.),
and is drawn into cold water inlet line 166 by a water pump 164 and fed
to a secondary heat exchanger 162. Refrigerant, returning from the load
heat exchanger 122 (usually an evaporator coil in a cooling duct) is
diverted from its normal path of the wet suction return 124 and fed to
the secondary heat exchanger 162 via secondary cooling line 170. Here,
the warm refrigerant is cooled by water entering from cold water inlet
line 166 and condenses, increasing the proportion of liquid in the
refrigerant which is then fed through a secondary cooling outlet line 172
to the primary heat exchanger 160. The header configuration drives most
of the liquid to the universal refrigerant management vessel 146 and the
vapor to the primary heat exchanger 160. This remaining refrigerant vapor
is then condensed within the primary heat exchanger 160 in the insulated
tank 140. After transferring heat to the refrigerant in the secondary
heat exchanger 162, the warmed water is returned to any portion (upper
portion depicted) of the insulated tank 140 via warm water return line
168.

[0024]The refrigerant management unit 104 includes the universal
refrigerant management vessel 146 which functions as an accumulator. The
universal refrigerant management vessel 146 is located on the
low-pressure side of the refrigerant circuitry and performs several
functions. The universal refrigerant management vessel 146 separates the
liquid-phase from the vapor-phase refrigerant during the refrigerant
energy storage period and again during the cooling period. The universal
refrigerant management vessel 146 also provides a static column of liquid
refrigerant during the refrigerant energy storage period that sustains
gravity circulation through the ice freezing/discharge coils 142 inside
the insulated tank 140. The dry suction return 114 provides low-pressure
vapor-phase refrigerant to compressor 110, within the air conditioner
unit 102, during a first thermal energy storage time period from an
outlet at the top of the universal refrigerant management vessel 146. A
wet suction return 124 is provided through an inlet in the top of the
upper header assembly 154 for connection to an evaporator (load heat
exchanger 123) during the second time period when the refrigerant energy
storage system provides cooling.

[0025]The first time period is the refrigerant energy storage time period
in which sensible heat and latent heat are removed from water causing the
water to freeze. The output of the compressor 110 is high-pressure
refrigerant vapor that is condensed to form high-pressure liquid. A valve
(not shown) on the outlet of the liquid refrigerant pump 120 (in the
pumped liquid supply line 122) controls the connection to the load unit
108, for example closing the connection when the liquid refrigerant pump
is stopped.

[0026]During the first time period, heat flows from high-pressure warm
liquid to the low-pressure cold liquid inside the oil still/surge vessel
116 which boils the cold liquid. The pressure rise resulting from the
vapor that forms during liquid boiling inside the oil still/surge vessel
116 causes the cold liquid to exit the oil still/surge vessel 116 and
moves it to the ice freezing/discharge coils 142 where it is needed for
proper system operation during the first time period. During the second
time period, warm high-pressure liquid no longer flows through the
high-pressure liquid supply line 112 because the compressor 110 inside
air conditioner unit 102 is off. Therefore, the aforementioned heat flow
from warm liquid to cold liquid ceases. This cessation permits liquid
from the universal refrigerant management vessel 146 and ice
freezing/discharge coils to flow back into the oil still/surge vessel 116
because the high internal vessel gas pressure during the first time
period no longer exists.

[0027]During the thermal energy storage period, high-pressure liquid
refrigerant flows from the air conditioner unit 102 to an internal heat
exchanger, which keeps all but a small amount of low-pressure liquid
refrigerant out of the oil still/surge vessel 116. The refrigerant that
is inside the vessel boils at a rate determined by two capillary tubes
(pipes). One capillary is the vent capillary 128 that controls the level
of refrigerant in the oil still/surge vessel 116. The second, the oil
return capillary 148, returns oil-enriched refrigerant to the compressor
110 within the air conditioner unit 102 at a determined rate. The column
of liquid refrigerant in the universal refrigerant management vessel 146
is acted on by gravity and positioning the oil still/surge vessel 116
near the bottom of the universal refrigerant management vessel 146 column
maintains a steady flow of supply liquid refrigerant to the oil
still/surge vessel 116 and into the thermal energy storage unit 106. The
surge function allows excess refrigerant during the cooling period to be
drained from the ice freezing/discharging coils 142 that are in the
insulated tank 140, keeping the surface area maximized for condensing
refrigerant during the second time period.

[0028]The physical positioning of the oil still/surge vessel 116, in
reference to the rest of the system, is a performance factor as an oil
still and as a surge vessel. This oil still/surge vessel 116 additionally
provides the path for return of the oil that migrates with the
refrigerant that must return to the compressor 110. The slightly
subcooled (cooler than the vapor-to-liquid phase temperature of the
refrigerant) high-pressure liquid refrigerant that exits the oil
still/surge vessel 116 flows through a mixed-phase regulator 132 during
which a pressure drop occurs.

[0029]As stated above, the refrigerant management unit 104 receives
high-pressure liquid refrigerant from the air conditioner unit 102 via a
high-pressure liquid supply line 112. The high-pressure liquid
refrigerant flows through the heat exchanger within the oil still/surge
vessel 116, where it is slightly subcooled, and then flows to the
mixed-phase regulator 132, where the refrigerant pressure drop takes
place. The use of a mixed-phase regulator 132 provides many favorable
functions besides liquid refrigerant pressure drop. The mass quantity of
refrigerant that passes through the mixed-phase regulator 132 matches the
refrigerant boiling rate inside the ice making coils 142 during the
thermal energy storage time period, thereby, eliminating the need for a
refrigerant level control.

[0030]The mixed-phase regulator 132 passes liquid refrigerant, but closes
when sensing vapor. The existence of vapor on the low side of the
regulator creates pressure to close the valve which combines with the
other forces acting upon the piston, to close the piston at a
predetermined trigger point that corresponds to desired vapor content.
This trigger point may be predetermined by regulator design (e.g.,
changing the geometry of the regulator components as well as the
materials). The trigger point may also be adjusted by automatic or manual
adjustments to the regulator geometry (e.g., threaded adjustment to the
piston displacement limits).

[0031]The pulsing action created in the refrigerant exiting the
mixed-phase regulator 132 as a result of the opening and closing of the
mixed-phase regulator 132 creates a pulsing effect upon the liquid
refrigerant that creates a pressure wave within the closed column in the
universal refrigerant management vessel 146. This agitates the liquid
refrigerant in both the ice making coils 142 and the condenser 111 during
the thermal energy storage first time period, and enhances heat transfer
as well as assists in segregating liquid and vapor-phase refrigerant. The
mixed-phase regulator 132, in conjunction with the universal refrigerant
management vessel 146, also drains the air conditioner unit 102 of liquid
refrigerant during the first time period keeping its condensing surface
area free of liquid condensate and therefore available for condensing.
The mixed-phase regulator 132 allows head pressure of the air-cooled air
conditioner unit 102 to float with ambient temperature. The system does
not require a superheat circuit, which is necessary with most condensing
units connected to a direct expansion refrigeration device.

[0032]The low-pressure mixed-phase refrigerant that leaves the mixed-phase
regulator 132 passes through a bifurcator 130 to an eductor (or injector
nozzle), located between the inlet, to the universal refrigerant
management vessel 146 and the upper header assembly 154 of the ice making
coils 142, to assist with gravity refrigerant circulation. During the
refrigerant thermal energy storage time period, the eductor creates a
drop in pressure immediately upstream from the eductor, and in the upper
header assembly 154 of the thermal energy storage unit 106, as the
refrigerant leaves the bifurcator 130, thereby increasing the rate of
refrigerant circulation in the ice making coils 142 while simultaneously
improving system performance.

[0033]The mixed-phase regulator 132 also reacts to changes in refrigerant
mass flow from compressor 110 as the pressure difference across its
outlet port varies with increasing or decreasing outdoor ambient air
temperatures. This allows the condensing pressure to float with the
ambient air temperature. As the ambient air temperature decreases, the
head pressure at the compressor 110 decreases which reduces energy
consumption and increases compressor 110 capacity. The mixed-phase
regulator 132 allows liquid refrigerant to pass while closing a piston
upon sensing vapor. Therefore, the mixed-phase regulator 132 temporarily
holds the vapor-phase mixture in a "trap". Upon sensing high-pressure
liquid, the piston lifts from its seat which allows liquid to pass.

[0034]The mixed-phase regulator 132 therefore, allows vapor pressure to
convert high-pressure liquid refrigerant to low-pressure liquid
refrigerant and flash vapor. The vapor held back by the mixed-phase
regulator 132 increases the line pressure back to the condenser 111 and
is further condensed into a liquid. The mixed-phase regulator 132 is self
regulating and has no parasitic losses. Additionally, the mixed-phase
regulator 132 improves the efficiency of the heat transfer in the coils
of the heat exchangers by removing vapor out of the liquid and creating a
pulsing action on both the low-pressure and high-pressure sides of the
system. As stated above, the mixed-phase regulator opens to let
low-pressure liquid through and then closes to trap vapor on the
high-pressure side and creates a pulsing action on the low-pressure side
of the regulator. This pulsing action wets more of the inside wall of the
heat exchanger at the boiling and condensing level, which aids in the
heat transfer.

[0035]The low-pressure mixed-phase refrigerant enters the universal
refrigerant management vessel 146 and the liquid and vapor components are
separated by gravity with liquid falling to the bottom and vapor rising
to the top. The liquid component fills the universal refrigerant
management vessel 146 to a level determined by the mass charge of
refrigerant in the system, while the vapor component is returned to the
compressor of the air conditioner unit 102. In a normal direct expansion
cooling system, the vapor component circulates throughout the system
reducing efficiency. With the embodiment depicted in FIG. 1, the vapor
component is returned to the compressor 110 directly without having to
pass though the evaporator. The column of liquid refrigerant in the
universal refrigerant management vessel 146 is acted upon by gravity and
has two paths during the thermal energy storage time period. One path is
to the oil still/surge vessel 116 where the rate is metered by capillary
tubes 128 and 148.

[0036]The second path for the column of liquid refrigerant is to the lower
header assembly 156, through the ice freezing/discharge coils 142 and the
upper header assembly 154, and back to the compressor 110 through the
universal refrigerant management vessel 146. This gravity assisted
circulation stores thermal capacity in the form of ice when the tank is
filled with a phase-change fluid such as water. The liquid static head in
the universal refrigerant management vessel 146 acts as a pump to create
a flow within the ice freezing/discharge coils 142. As the refrigerant
becomes a vapor, the level of liquid in the coil is forced lower than the
level of the liquid in the universal refrigerant management vessel 146,
and therefore, promotes a continuous flow between the universal
refrigerant management vessel 146 through ice freezing/discharge coils
142. This differential pressure between the universal refrigerant
management vessel 146 and the ice freezing/discharge coils 142 maintains
the gravity circulation. Initially vapor only, and later (in the storage
cycle), both refrigerant liquid and vapor, are returned to the universal
refrigerant management vessel 146 from the upper header assembly 154.

[0037]As refrigerant is returned to the universal refrigerant management
vessel 146 the heat flux gradually diminishes due to increasing ice
thickness (increasing thermal resistance). The liquid returns to the
universal refrigerant management vessel 146 within the refrigerant
management unit 104 and the vapor returns to the compressor 110 within
the air conditioner unit 102. Gravity circulation assures uniform
building of the ice. As one of the ice freezing/discharge coils 142
builds more ice, its heat flux rate is reduced. The coil next to it now
receives more refrigerant until all coils have a nearly equal heat flux
rate.

[0038]The design of the ice freezing/discharge coils 142 creates an ice
build pattern that maintains a high compressor suction pressure
(therefore an increased suction gas density) during the ice build storage
(first) time period. During the final phase of the thermal energy storage
(first) time period, all remaining interstices between each ice
freezing/discharge coil 142 become closed with ice, therefore the
remaining water to ice surface area decreases, and the suction pressure
drops dramatically. This drop on suction pressure can be used as a full
charge indication that automatically shuts off the condensing unit with
an adjustable refrigerant pressure switch.

[0039]When the air conditioner unit 102 turns on during the thermal energy
storage first time period, low-pressure liquid refrigerant is prevented
from passing through the liquid refrigerant pump 120 by gravity, and from
entering the load heat exchanger 123 by a poppet valve (not shown) in the
pumped liquid supply line 122. When the thermal energy storage system is
fully charged, and the air conditioning unit 102 shuts off, the
mixed-phase regulator 132 allows the refrigerant system pressures to
equalize quickly. This rapid pressure equalization permits use of a high
efficiency, low starting torque motor in the compressor 110. The load
heat exchanger 123 is located either above or below the thermal energy
storage unit 106 so that refrigerant may flow from the load heat
exchanger 123 (as mixed-phase liquid and vapor), or through the wet
suction return 124 (as vapor only at saturation), to the upper header
assembly 154. After passing through the upper header assembly 154 it then
passes into the ice freezing/discharge coils for condensing back to a
liquid.

[0040]As shown in FIG. 1, an embodiment of a high efficiency refrigerant
energy storage and cooling system is depicted comprising the five major
components that define the system. The air conditioner unit 102 is a
conventional condensing unit that utilizes a compressor 110 and a
condenser 111 to produce high-pressure liquid refrigerant delivered
through a high-pressure liquid supply line 112 to the refrigeration
management unit 104. The refrigeration management unit 104 is connected
to a thermal energy storage unit 106 comprising an insulated tank 140
filled with water and ice-making coils 142. Finally, a secondary heat
exchanger unit 162 introduces external melt capability providing
additional instantaneous cooling load to the system. The air conditioner
unit 102, the refrigeration management unit 104 and the thermal energy
storage unit 106 act in concert to provide efficient multi-mode cooling
to the load heat exchanger 108 (indoor cooling coil assembly) and thereby
perform the functions of the principal modes of operation of the system.
The circulation loop created with the secondary heat exchanger 162
transfers heat between the refrigerant leaving the load heat exchanger
123 and the fluid within the insulated tank 140. This loop acts to
circulate and destratify fluid 152 within the insulated tank 140 and draw
heat from refrigerant leaving the load heat exchanger 123. This secondary
heat exchanger loop can be switched in and out of the system by valves
188 as necessary when instantaneous cooling load is needed. The system
shown is known as an internal/external melt system because the thermal
energy that has been stored in the form of ice is melted internally to
the block by freezing/discharging coils 142 and externally by circulating
cold water from the periphery of the block through a secondary heat
exchanger 162. This secondary heat exchanger loop can be switched in and
out of the system by valves 188 as necessary when instantaneous cooling
load is needed.

[0041]FIG. 2 illustrates an embodiment of a refrigerant-based thermal
energy storage cooling system with enhanced heat exchange capability. A
thermal energy storage and cooling system with a conventional condensing
unit 202 (air conditioner) utilizes a compressor and condenser to produce
high-pressure liquid refrigerant delivered through a high-pressure liquid
supply line 212 to the refrigeration management and distribution system
204 which can include a universal refrigerant management vessel 246 and a
liquid refrigerant pump 220. The universal refrigerant management vessel
246 receives the low-pressure mixed phase 262 liquid refrigerant that has
been dropped in pressure from the high-pressure liquid supply line 212.
Refrigerant is accumulated in a universal refrigerant management vessel
246 that separates the liquid-phase refrigerant from the vapor-phase
refrigerant. A mixed-phase regulator (not shown) can be used to minimize
vapor feed to the universal refrigerant management vessel 246 from the
compressor, while decreasing the refrigerant pressure difference from the
condenser to the evaporator saturation pressure.

[0042]In thermal energy storage mode, the universal refrigerant management
vessel 246 feeds liquid refrigerant through liquid feed line 266 to the
primary heat exchanger 260 that stores the cooling (thermal energy) in
the form of ice or an ice block 242. Upon delivering the cooling to the
primary heat exchanger 260, mixed-phase refrigerant is returned to the
universal refrigerant management vessel 246 via a wet suction return line
224. Dry suction return line 218 returns vapor phase refrigerant to be
compressed and condensed in the condensing unit 202 to complete the
thermal energy storage cycle.

[0043]In cooling mode, the universal refrigerant management vessel 246
feeds liquid refrigerant through pump inlet line 264 to a liquid
refrigerant pump 220 which then pumps the refrigerant to an evaporator
coil 222 via pump outlet line 260. Upon delivering the cooling to the
evaporator coil 222, mixed-phase or saturated refrigerant is returned to
the primary heat exchanger 260 via a low-pressure vapor line 268 and is
condensed and cooled utilizing an ice block 242 that is made during
thermal energy storage mode. The vapor-phase refrigerant is then returned
to the universal refrigerant management vessel 246 via liquid feed line
266. A secondary heat exchanger unit 270 introduces an external melt to
the system to provide additional instantaneous cooling load to the
system. By providing a system with internal/external melt capability,
thermal energy stored in the form of an ice block 242 is melted
internally by freezing/discharging coils within the primary heat
exchanger 260 and externally by circulating cold water from the periphery
of the block through the secondary heat exchanger 270. This allows the
system to realize as much as a fourfold increase in instantaneous cooling
capacity.

[0044]During this second time period (cooling mode), warm vapor phase
refrigerant circulates through ice freezing/discharging coils within the
primary heat exchanger 260 and melts the ice block 242 from the inside
out, providing a refrigerant condensing function. As heat is transferred
from these ice freezing/discharging coils to the surrounding ice block
242, a layer of water forms around the annulus of the individual coils.
As described above, once this layer of water forms a sufficient envelope
around a coil, it begins to act as an insulator between the ice
freezing/discharging coils and the ice block 242. This condition will
persist until such a time when the water annulus becomes large enough for
considerable water circulation to overcome this localized thermal
stratification. In order to compensate for the inability of the system to
produce high levels of instantaneous cooling load, the outer surface of
the ice block is additionally utilized.

[0045]Within the insulated tank 240, the entirety of the water is not
frozen during the ice build cycle, and therefore, an amount of water
continuously surrounds the block of ice. At the bottom of the insulated
tank 240, this water is very near the freezing point (approximately
33-34° F.), and is drawn into cold water line 274 by a water pump
272 and fed to the secondary heat exchanger 270. Refrigerant, returning
from the evaporator coil 222 can be diverted from its normal path of the
wet suction return 224 and fed to the secondary heat exchanger 270 via
secondary cooling inlet line 278. Here, the warm refrigerant is cooled by
water entering from cold water line 274 and condenses, increasing the
proportion of liquid in the refrigerant which is then fed through a
secondary cooling outlet line 280 to the primary heat exchanger 260 where
the header configuration drives most of the liquid to the universal
refrigerant management vessel 246 and the vapor to the primary heat
exchanger 260. This remaining refrigerant vapor is then condensed within
the primary heat exchanger 260 in the insulated tank 240. After
transferring heat to the refrigerant in the secondary heat exchanger 270,
the warmed water is returned to the upper portion of the insulated tank
240 via warm water return line 276. This secondary heat exchanger loop
can be switched in and out of the system by valves 288 as necessary when
instantaneous cooling load is needed. Additionally, a secondary cooling
source (not shown), such as an external cold water line or the like, may
be placed in thermal contact with the refrigerant in the secondary heat
exchanger to additionally boost the pre-cooling of the refrigerant
entering the primary heat exchanger 260 or the URMV 246.

[0046]FIG. 3 illustrates an embodiment of a refrigerant-based thermal
energy storage and cooling system with multiple enhanced heat exchanger
capability. Similarly, as is detailed above in the previous Figures, a
thermal energy storage and cooling system with a conventional condensing
unit 302 (air conditioner) utilizes a compressor and condenser to produce
high-pressure liquid refrigerant delivered through a high-pressure liquid
supply line to the refrigeration management and distribution system 304
which can include a universal refrigerant management vessel 346 and a
liquid refrigerant pump 320. A mixed-phase flow regulator (not shown) may
be used to receive high-pressure liquid refrigerant from the
high-pressure liquid supply line and regulate the flow of refrigerant fed
from the compressor to the heat load. Low-pressure mixed-phase
refrigerant is accumulated in a universal refrigerant management vessel
346 that separates the liquid phase from the vapor phase refrigerant.

[0047]In thermal energy storage mode, the universal refrigerant management
vessel 346 feeds liquid refrigerant through a liquid line feed to the
primary heat exchanger 360 that stores the cooling in the form of ice or
an ice block 342. Upon delivering the cooling to the primary heat
exchanger 360, mixed-phase refrigerant is returned to the universal
refrigerant management vessel 346 via a wet suction return line 324. A
dry suction return line returns vapor phase refrigerant to be compressed
and condensed in the condensing unit 302 to complete the thermal energy
storage cycle.

[0048]In cooling mode, the universal refrigerant management vessel 346
feeds liquid refrigerant to a liquid refrigerant pump 320, which then
pumps the refrigerant to an evaporator coil 322. Upon delivering the
cooling to the evaporator coil 322, mixed-phase refrigerant is returned
to the primary heat exchanger 360 and cooled utilizing an ice block 342
that is made during thermal energy storage mode. The vapor phase
refrigerant is condensed into liquid by the ice cooling, and returned to
the universal refrigerant management vessel 346 via liquid feed line 366.
A secondary heat exchanger unit 370 and a tertiary heat exchanger unit
390 introduce an external melt to the system to provide additional
instantaneous cooling load to the system.

[0049]By providing a system with internal/external melt capability,
thermal energy stored in the form of an ice block 342 is melted
internally by freezing/discharging coils within the primary heat
exchanger 360 and externally by circulating cold water from the periphery
of the block through the secondary and tertiary heat exchangers 370 and
390. This allows the system to react to very large instantaneous cooling
demands. Additional heat exchange units can be added to the system in the
manner of tertiary heat exchanger 390 to regulate a wide variety of
cooling load demands. During this second time period (cooling mode), warm
vapor phase refrigerant circulates through ice freezing/discharging coils
within the primary heat exchanger 360 and melts the ice block 342 from
the inside out providing a refrigerant condensing function.

[0050]Water at the bottom of the insulated tank 340 is drawn into cold
water line 374 by a water pump 372 and fed to the secondary and tertiary
heat exchangers 370 and 390. Refrigerant, returning from the evaporator
coil 322 can be diverted from its normal path of the wet suction return
324 and fed to the secondary and tertiary heat exchangers 370 and 390 via
secondary cooling inlet line 378. Here, the warm refrigerant is cooled by
water entering from cold water line 374 and condenses, increasing the
proportion of liquid in the refrigerant which is then fed through a
secondary cooling outlet line 380 to the primary heat exchanger 360 where
the header configuration drives most of the liquid to the universal
refrigerant management vessel 346 and the vapor to the primary heat
exchanger 360. This remaining refrigerant vapor is then condensed within
the primary heat exchanger 360 in the insulated tank 340. After
transferring heat to the refrigerant in the secondary and tertiary heat
exchangers 370 and 390, the warmed water is returned to the upper portion
of the insulated tank 340 via warm water return line 376. These secondary
and tertiary heat exchanger loops can be switched in and out of the
system by valves 388 as necessary when instantaneous cooling load is
needed. A plurality of additional heat exchangers can be added to the
system in a similar manner to the tertiary heat exchanger in series or
parallel to accomplish additional enthalpy reduction of the refrigerant
if needed.

[0051]FIG. 4 illustrates an embodiment of a refrigerant-based thermal
energy storage cooling system with enhanced heat exchange capability
utilizing a shared fluid bath. A thermal energy storage and cooling
system with a conventional condensing unit 402 (air conditioner) utilizes
a compressor and condenser to produce high-pressure liquid refrigerant
delivered through a high-pressure liquid supply line 412 to the
refrigeration management and distribution system 404 which can include a
universal refrigerant management vessel 446 and a liquid refrigerant pump
420. The universal refrigerant management vessel 446 receives the
low-pressure mixed phase 462 liquid refrigerant that has been dropped in
pressure from the high-pressure liquid supply line 412. Refrigerant is
accumulated in the universal refrigerant management vessel 446 that
separates the liquid-phase refrigerant from the vapor-phase refrigerant.
Low-pressure mixed-phase refrigerant 462 is accumulated in a universal
refrigerant management vessel 446 that separates the liquid-phase
refrigerant from the vapor-phase refrigerant. A mixed-phase regulator
(not shown) can be used to minimize vapor feed to the universal
refrigerant management vessel 446 from the compressor, while decreasing
the refrigerant pressure difference from the condenser to the evaporator
saturation pressure.

[0052]In thermal energy storage mode, the universal refrigerant management
vessel 446 feeds liquid refrigerant through liquid feed line 466 to the
primary heat exchanger 460 that stores the cooling (thermal energy) in
the form of ice or an ice block 442. Upon delivering the cooling to the
primary heat exchanger 460, mixed-phase refrigerant is returned to the
universal refrigerant management vessel 446 via a wet suction return line
424. Dry suction return line 418 returns vapor phase refrigerant to be
compressed and condensed in the condensing unit 402 to complete the
thermal energy storage cycle.

[0053]In cooling mode, the universal refrigerant management vessel 446
feeds liquid refrigerant through pump inlet line 464 to a liquid
refrigerant pump 420 which then pumps the refrigerant to an evaporator
coil 422 via pump outlet line 460. Upon delivering the cooling to the
evaporator coil 422, mixed-phase or saturated refrigerant is returned to
the primary heat exchanger 460 via a low-pressure vapor line 468 and is
condensed and cooled utilizing an ice block 442 that is made during
thermal energy storage mode. The vapor-phase refrigerant is then returned
to the universal refrigerant management vessel 446 via liquid feed line
466. A secondary heat exchanger unit 470, located within the fluid 443
that is contained inside of the insulated tank 440 but outside of the ice
block 442, may be used to introduce an external melt and provide
additional instantaneous cooling load to the system in a serial
configuration. By providing a system with internal/external melt
capability, thermal energy stored in the form of an ice block 442 is
melted internally by freezing/discharging coils within the primary heat
exchanger 460 and externally by circulating/and or contacting fluid from
the periphery of the block with the secondary heat exchanger 470. This
allows the system to realize increased instantaneous cooling capacity in
a simple and self contained manner. An additional circulating pump or air
pump may be utilized to destratify and mix the fluid within the chamber.

[0054]During this second time period (cooling mode), warm vapor phase
refrigerant circulates through ice freezing/discharging coils within the
primary heat exchanger 460 and melts the ice block 442 from the inside
out, providing a refrigerant condensing function. As heat is transferred
from these ice freezing/discharging coils to the surrounding ice block
442, a layer of water forms around the annulus of the individual coils.
As described above, once this layer of water forms a sufficient envelope
around a coil, it begins to act as an insulator between the ice
freezing/discharging coils and the ice block 442. This condition will
persist until such a time when the water annulus becomes large enough for
considerable water circulation to overcome this localized thermal
stratification. In order to compensate for the inability of the system to
produce high levels of instantaneous cooling load, the outer surface of
the ice block is additionally utilized.

[0055]Within the insulated tank 440, the entirety of the water is not
frozen during the ice build cycle, and therefore, an amount of water
continuously surrounds the block of ice. At the bottom of the insulated
tank 440, this water is very near the freezing point (approximately
33-34° F.), and is used to contact the secondary heat exchanger
470 located within the fluid 443. Refrigerant, returning from the
evaporator coil 422 can be diverted from its normal path of the wet
suction return 424 and fed to the secondary heat exchanger 470 via
secondary cooling inlet line 480. Here, the warm refrigerant is cooled by
water surrounding the ice block 442 and condenses, increasing the
proportion of liquid in the refrigerant which is then fed through a
secondary cooling outlet line 480 to the primary heat exchanger 460 where
the header configuration drives most of the liquid to the universal
refrigerant management vessel 446 and the vapor to the primary heat
exchanger 460. This remaining refrigerant vapor is then condensed within
the primary heat exchanger 460 in the insulated tank 440. After
transferring heat to the refrigerant in the secondary heat exchanger 470,
the warmed water is circulated and mixed within the insulated tank 440.
This secondary heat exchanger loop can be switched in and out of the
system by valves 488 as necessary when instantaneous cooling load is
needed.

[0056]FIG. 5 illustrates an embodiment of a refrigerant-based thermal
energy storage cooling system with enhanced heat exchange capability
utilizing a shared fluid bath. A thermal energy storage and cooling
system with a conventional condensing unit 502 (air conditioner) utilizes
a compressor and condenser to produce high-pressure liquid refrigerant
delivered through a high-pressure liquid supply line 512 to the
refrigeration management and distribution system 504 which can include a
universal refrigerant management vessel 546 and a liquid refrigerant pump
520. The universal refrigerant management vessel 546 receives the
low-pressure mixed phase 562 liquid refrigerant that has been dropped in
pressure from the high-pressure liquid supply line 512. Refrigerant is
accumulated in the universal refrigerant management vessel 546 that
separates the liquid-phase refrigerant from the vapor-phase refrigerant.
Low-pressure mixed-phase refrigerant 562 is accumulated in a universal
refrigerant management vessel 546 that separates the liquid-phase
refrigerant from the vapor-phase refrigerant. A mixed-phase regulator
(not shown) can be used to minimize vapor feed to the universal
refrigerant management vessel 546 from the compressor, while decreasing
the refrigerant pressure difference from the condenser to the evaporator
saturation pressure.

[0057]In thermal energy storage mode, the universal refrigerant management
vessel 546 feeds liquid refrigerant through liquid feed line 566 to the
primary heat exchanger 560 that stores the cooling (thermal energy) in
the form of ice or an ice block 542. Upon delivering the cooling to the
primary heat exchanger 560, mixed-phase refrigerant is returned to the
universal refrigerant management vessel 546 via a wet suction return line
524. Dry suction return line 518 returns vapor phase refrigerant to be
compressed and condensed in the condensing unit 502 to complete the
thermal energy storage cycle.

[0058]In cooling mode, the universal refrigerant management vessel 546
feeds liquid refrigerant through pump inlet line 564 to a liquid
refrigerant pump 520 which then pumps the refrigerant to an evaporator
coil 522 via pump outlet line 560. Upon delivering the cooling to the
evaporator coil 522, mixed-phase or saturated refrigerant is returned to
the primary heat exchanger 560 via a low-pressure vapor line 568 and is
condensed and cooled utilizing an ice block 542 that is made during
thermal energy storage mode. The vapor-phase refrigerant is then returned
to the universal refrigerant management vessel 546 via liquid feed line
566. A secondary heat exchanger unit 570, located within the fluid 543
that is contained inside of the insulated tank 540 but outside of the ice
block 542, may be used to introduce an external melt and provide
additional instantaneous cooling load to the system in a parallel
configuration. By providing a system with simultaneous internal and
external melt capability, thermal energy stored in the form of an ice
block 542 is melted internally by freezing/discharging coils within the
primary heat exchanger 560 and externally by circulating/and or
contacting fluid from the periphery of the block with the secondary heat
exchanger 570. This allows the system to realize increased instantaneous
cooling capacity in a simple and self contained manner. An additional
circulating pump or air pump may be utilized to destratify and mix the
fluid within the chamber.

[0059]During this second time period (cooling mode), warm vapor phase
refrigerant circulates through ice freezing/discharging coils within the
primary heat exchanger 560 and melts the ice block 542 from the inside
out, providing a refrigerant condensing function. As heat is transferred
from these ice freezing/discharging coils to the surrounding ice block
542, a layer of water forms around the annulus of the individual coils.
As described above, once this layer of water forms a sufficient envelope
around a coil, it begins to act as an insulator between the ice
freezing/discharging coils and the ice block 542. This condition will
persist until such a time when the water annulus becomes large enough for
considerable water circulation to overcome this localized thermal
stratification. In order to compensate for the inability of the system to
produce high levels of instantaneous cooling load, the outer surface of
the ice block is additionally utilized.

[0060]Within the insulated tank 540, the entirety of the water is not
frozen during the ice build cycle, and therefore, an amount of water
continuously surrounds the block of ice. At the bottom of the insulated
tank 540, this water is very near the freezing point, and is used to
contact the secondary heat exchanger 570 located within the fluid 543.
Refrigerant, returning from the evaporator coil 522 can be diverted from
its normal path of the wet suction return 524 and fed simultaneously to
the secondary heat exchanger 570 and the primary heat exchanger 560 via
secondary cooling inlet line 580. Here, the warm refrigerant is cooled by
water surrounding the ice block 542 by secondary heat exchanger 570 and
the primary heat exchanger 560 within the ice block 542 and condenses.
The header configuration then drives most of the liquid to the universal
refrigerant management vessel 546 and the vapor to the primary heat
exchanger 560 and the secondary heat exchanger 570. Remaining refrigerant
vapor is eventually condensed within the primary heat exchanger 560 in
the insulated tank 540. After transferring heat to the refrigerant in the
secondary heat exchanger 570, the warmed water is circulated and mixed
within the insulated tank 540. This secondary heat exchanger loop can be
switched in and out of the system by valve 590 as necessary when
instantaneous cooling load is needed.

[0061]Conventional thermal energy storage units that utilize a
refrigerant-based, internal melt, ice on coil system, are constrained by
a cooling load capacity that is limited by the heat transfer coefficient
of the ice melt. In such a system, a condensing unit is used to store
refrigerant energy during one time period in the form of ice (ice build),
and provide cooling from the stored ice energy during a second time
period (ice melt). This melt process typically starts on the outside of a
heat transfer tube of a heat exchanger that is imbedded within the block
of ice, through which warm refrigerant flows. As heat is transferred
through the heat exchanger to the ice, an annulus of water forms between
the tubes and the ice, and in the absence of circulation, acts as an
insulator to further heat transfer. Thus, the capacity of the heat
exchanger is limited in the early stages of the melt prior to a time when
a large enough water annulus allows mixing of the water in the area of
the ice block. Previous attempts to improve heat transfer between a heat
transfer tube that is surrounded by ice have involved creating turbulence
by bubbling air in the jacket of water. This method is limited by poor
efficiency, reliability and high cost (both energy and dollars).

[0062]The present invention overcomes the disadvantages and limitations of
the prior art by providing a method and device to increase the cooling
load that can be provided by a refrigerant-based thermal energy storage
and cooling system with an improved arrangement of heat exchangers. This
is accomplished by circulating cold water surrounding a block of ice,
used as the thermal energy storage medium, through a secondary heat
exchanger where it condenses refrigerant vapor returning from a load. The
refrigerant is then circulated through a primary heat exchanger within
the block of ice where it is further cooled and condensed. This system is
known as an internal/external melt system because the thermal energy,
stored in the form of ice, is melted internally by a primary heat
exchanger and externally by circulating cold water from the periphery of
the block through a secondary heat exchanger.

[0063]In a typical ice storage unit, the water in the tank that surrounds
the periphery of the ice never freezes solid. This water remains
approximately 32° F. at the bottom of the tank for nearly the
entirety of the melt period. By circulating this water through a
secondary heat exchanger and then back into the tank with a small
circulation pump, greater heat exchange efficiencies can be realized. The
secondary heat exchanger is a high-efficiency heat exchanger such as a
coaxial condenser or a brazed plate heat exchanger or the like and is
used to lower the enthalpy (lower the temperature and/or condense) the
refrigerant prior to entering the main heat exchanger in the ice tank. As
a result, the total cooling capacity of the system is now the sum of the
capacities provided by the two heat exchangers. By using as many of the
secondary heat exchangers as needed, the system can provide the
flexibility to match the ice storage system to the requirement of the
cooling load.

[0064]The detailed embodiments detailed above, minimize additional
components and use very little energy beyond that used by the condensing
unit to store the thermal energy. The refrigerant energy storage design
has been engineered to provide flexibility so that it is practicable for
a variety of applications. The embodiments can utilize stored energy to
provide chilled water for large commercial applications or provide direct
refrigerant air conditioning to multiple evaporators. The design
incorporates multiple operating modes, the ability to add optional
components, and the integration of smart controls that guarantee energy
is stored at maximum efficiency. When connected to a condensing unit, the
system stores refrigeration energy in a first time period, and utilizes
the stored energy during a second time period to provide cooling. In
addition, both the condensing unit and the refrigerant energy storage
system can operate simultaneously to provide cooling during a third time
period.

[0065]Numerous advantages are realized in utilizing additional heat
exchanger loops to manage coolant in high-efficiency thermal energy
storage and cooling systems. The embodiments described can increase the
cooling capacity of the system by as much as 400% to match the cooling
load required. The system eliminates complicated and expensive air
distribution systems that are subject to great reliability concerns and
the system can readily adapt to buildings cooled by cold-water
distribution. These embodiments have widespread application in all
cooling systems, extending beyond applications for air-conditioning. For
instance, this method can be used for cooling any fluid medium using ice
storage. Combined with an efficient method of making ice, these
embodiments can have wide application in dairy, and petroleum industries.

[0066]The foregoing description of the invention has been presented for
purposes of illustration and description. It is not intended to be
exhaustive or to limit the invention to the precise form disclosed, and
other modifications and variations may be possible in light of the above
teachings. The embodiment was chosen and described in order to best
explain the principles of the invention and its practical application to
thereby enable others skilled in the art to best utilize the invention in
various embodiments and various modifications as are suited to the
particular use contemplated. It is intended that the appended claims be
construed to include other alternative embodiments of the invention
except insofar as limited by the prior art.